Some customers ask us why they can't choose a 'preview frame' for their videos. This is when you (in the Instagram app) scroll to the frame that you want people to see before clicking on the play button to watch the video in their feed.
Unfortunately at this time we can't support choosing the frame for technical reasons.
Because of how choosing these cover images works, it would require highly precise "swiping" calculations on our side, and we simply wouldn't be able to do it in an accurate and reliable manner. Until something changes like that, we just use the default - which we believe currently is the first frame for most videos. So if the first frame is black/blank, the thumbnail will be black/blank.
You have two options for the preview frame that we choose for your videos. The options are "all or nothing" - unfortunately you need to choose one or the other for all of your videos.
You can change option for each of your Instagram accounts by going to 'manage accounts' > 'account settings' and then changing the video frame option:
(1) Default - Instagram's default choice - the first frame of the video
This is the first frame of the video, or whatever Instagram chooses as the default (we don't touch or change what is shown on the picker screen). This is the default option, and what most accounts will be set as.
(2) Middle frame
This is where we click the exact middle 'window' shown in the Instagram app. It should be roughly the middle frame of the video (although this isn't a precise thing).